[CONTRIBUTION FROM THE B A K E R LABORATORY O F CHEMISTRY AT CORNELL UNIVERSITY]
UNSATURATED NITRILES AS DIENOPHILES I N THE DIENE SYNTHESIS A. T.BLohfQUIST AND E.
c. WINSLOW
Received December 14, 1944 INTRODUCTION
The extensive efforts which have been made to produce a synthetic insecticide superior in all respects to pyrethrum have been only moderately successful. A recent approach t o the problem has been through the Diels-Alder diene synthesis which affords substances whose molecular structure closely resembles the active principles of pyrethrum. Comparison of the pyrethrins with compounds derived from endo-cis-1,2,3,6-tetrahydro-3,6-methanophthalicanhydride (I) reveals that all contain an unsaturated five-membered ring and some contain 8 gamma-delta double bond.
I From preliminary studies carried out in this laboratory by Johnson and McCrone ( 1 ) there are indications that certain N-alkyl imides derived from I may be effective insecticides. Of further interest is the recent observation of other investigators (2) that phthalonitrile is relatively highly toxic t o a number of species of insects. The present study was inspired by the possibility that substances of improved insecticidal properties might be obtained through a combination of the structural features of the hydromethanophthalic anhydrides and phthalonitrile. Such compounds may be considered to be derived from the parent structure 3,6dihydro-3,6-methanophthalonitrile (11).
I1 149
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A. T. BLOMQUIST AND E. C. WINSLOW
The diene synthesis using cyclopentadiene and non-carbonylic dienophiles such as fumaronitrile, maleonitrile, and acetylenedicarbonitrile has been found to take place with extreme ease to form the corresponding nitriles (111, IV, and VI.
111
v
IV
Catalytic hydrogenation of 111 and IV yields the corresponding cis- and trans hexahydro-3,6-methanophthalonitriiles (VI and VII). Selective hydrogenation of the A4 double bond in V to form the tetrahydrophthalonitfile (VIII) also appears to have been effected.
VI
VI1
VI11
In addition to the nitriles described above, a second series of adducts has been obtained through a diene synthesis involving diphenylfulvene with the three unsaturated dinitriles. The several 3 ,6-benzohydrilidenemethanophthalonitriles obtained are shown in IX, X, and XI.
9-c-9 I1
C
@-c-@
9-C-U) II
I1
C
C
&iCN &c IH'
,-CN
CN
H
IX
X
CN
XI
Preliminary insecticidal tests on all of the above nitriles have been carried out with the silkworm and Colorado potato beetle. The results indicate that the compounds act as contact poisons and not as stomach poisons. The most effective nitriles are those which contain the A4 double bond. Of these, the compounds I11 and IV show the most promise.
UNSATURATED NITRILES I N THE DIENE SYNTHESIS
151
DISCUSSION
Exploratory investigation of a number of possible methods of synthesis of the nitriles mentioned above disclosed a number of interesting details concerning the chemistry of endo-cis-1,2,3 ,6-tetrahydro-3,6-methanophthalicanhydride (I) and its derivatives. These observations together with the results of the diene syntheses involving the nitrile dienophiles are closely related and may conveniently be discussed at the same time. Throughout this article the general principles of the stereochemistry of the diene synthesis as established by Alder and Stein (3)have been assumed to hold. The important principles are the following; the addition of a diene to a dienophile invariably results in cis- addition and, prior to the consummation of addition, the molecules are so oriented as to permit a maximum accumulation of double bonds. Thus the addition of cyclopentadiene to maleonitrile gives exclusively the “endo” configuration of a cis-nitrile whereas the ‘‘exo” configuration is realized in the addition of diphenylfulvene to such a dienophile. An excellent review of these principles is to be found in Norton’s summary of the Diels-Alder diene synthesis (4). DERIVATIVES OF
1 ,2 ,3 ,6-TETRAHYDR0-3,6-METEiANOPHTHALIC ACID
The first attempts t o prepare the endo-cis- and trans-1 ,2 ,3,6-tetrahydro-3 ,6methanophthalonitriles (I11 and IV) were from the corresponding amides. The preparation of the amides from the acid chlorides, methyl esters, and the cyclic imide was studied. endo-cis- and trans-1 ,W ,3,6-Tetrahydro-S,6-methanophthalyl chlorides. The trans-acid chloride, b.p. 114-118”/11 mm., was readily obtained by the addition of fumaryl chloride to cyclopentadiene as described by Alder, Stein, et al. (5). Treatment of cis-1 ,2 ,3,6-tetrahydro-3,6-methanophthalic anhydride with phosphorus pentachloride, according to the procedure of Ott (6) for o-phthalyl chloride, gave a mixture of acid chlorides boiling over a wide range, 120-165”/14 mm., which probably consisted of the cis- and trans-acid chlorides as indicated by the mixture of amides obtained therefrom. The preparation of the pure 15sacid chloride through the addition of maleyl chloride to cyclopentadiene was not realized because maleyl chloride could not be obtained by the method of Clemmenson and Miller (7). Dimethyl endo-cis- and trans-1 ,W,3,6-tetrahydro-3,6-methanophthalates.Interaction of the trans-acid chloride described above with absolute methanol a t 30” gives a liquid ester (b.p. 119-120”/4 mm.). Comparison of this ester with the product obtained by Alder, Stein, et al. (8) in the addition of methyl maleate t o cyclopentadiene and with the ester obtained by Morgan et al. (9) in the alcoholysis of cis-tetrahydro-3,6-methanophthalicanhydride indicates that they are identical and probably have the trans-configuration. All of these liquid products are contaminated with traces of the anhydride. Removal of this contaminant with anhydrous gaseous ammonia gives a pure ester which solidifies on standing, m.p. 37-39’. Saponification of the dimethyl ester prepared by any of the above
152
A. T. BLOMQUIST AND E. C. WINSLOW
procedures gives exclusively the trans-acid, m.p. 186-187'. The extreme lability of the cis-ester is indicated by the observation that treatment of the cis-acid (m.p. 177-179') with diazomethane at 0' affords only the trans-ester on distillation. It was also observed that the same ease of isomerization is characteristic of the cis-form of the free acid. When the cis-acid is refluxed in xylene for two hours it is completely transformed to the trans-acid. The configuration of trans-1 ,2,3,6-tetrahydr0-3,6-methanophthalicacid (m.p. 186-187') has been confirmed by the resolution of its brucine salt. The pure d-acid, m.p. 166-168', showing the specific rotation +89.0' in acetone, was isolated. endo-cis- and trans-I ,2 ,3,6-Tetrahydro-S,6-methanophthalamides. The pure trans-amide was obtained by ammonolysis of the trans-acid chloride with aqueous ammonia, m.p. 253-256' (decomp.). Alkaline hydrolysis of the trans-amide gave the trans-acid. The trans-amide could not be obtained by ammonolysis of the corresponding trans-dimethyl ester under any conditions. Ammonolysis of the mixture of cis- and trans-acid chlorides described above gave a product (m.p. 235-240', decomp.) which appeared to be a mixture of the cis- and trans-amides. Preparation of the pure cis-amide by ammonolysis of endo-cis-1,2,3, &tetrahydro-3 ,6-methanophthalimide was tried without success. endo-cis-I ,2,3 ,6-Tetrahydro-3,6-methanophthalimide. By refluxing the ammonium salt of cis-tetrahydromethanophthalicacid with acetic anhydride the cyclic imide was obtained in good yield, m.p. 184-185'. Confirmation of the cis-configuration for the imide was obtained by effecting its synthesis through the addition of cyclopentadiene to maleimide. Identity of the two imides was established by a mixed melting point determination. The imide could not be obtained by ammonolysis of the related cyclic anhydride. Alkaline hydrolysis of the cis-imide yielded the trans-acid. endo-cis- and trans-I ,2 , 3 ,6-Tetrahydro-3,6-methanophthalonitriles. Prolonged heating of trans-tetrahydromethanophthalamide in acetic anhydride gave a small yield of two isomeric nitriles which could be separated by fractional crystallization. The less soluble nitrile melted a t 155-156' and the more soluble isomer at 95-96'. The nature of these nitriles was established by diene syntheses. The addition of fumaronitrile to cyclopentadiene gave an excellent yield of the truns-nitrile, m.p. 95-96', identical with the more soluble nitrile described above. Alkaline hydrolysis of this trans-nitrile gave the related trans-acid, m.p. 186187'. The addition of maleonitrile, prepared by the method of de Wolfe and van de Straete (lo), to cyclopentadiene proceeded smoothly t o give a high yield of the cis-nitrile, m.p. 155-156', identical with the less soluble of the two nitriles mentioned above. All attempts to hydrolyze this cis-nitrile in either acidic or basic media failed. Decomposition of the cis-nitrile in the hydrolysis was indicated by the formation of hydrogen cyanide. The formation of both the cis- and trans-nitriles upon treatment of the trans-
UNSATURATED KITRILES IN THE DIENE SYNTHESIS
153
amide with acetic anhydride is indicative of a trans to cis isomerization. The transformation might conceivably arise from the high temperature involved in the dehydration or from a particular effect of acetic anhydride. However, the trans-nitrile is recovered unchanged after prolonged heating in either boiling xylene or acetic anhydride. Thus it is indicated that isomerization probably occitrs prior t o the dehydration of the amide or during the course of the reaction. DERIVATIVES OF
3 6-DIHYDRO-3,6-METHANOPHTHALICACID
3 ,6-Dihydro-3 6-methanophthalamide. Ammonolysis of dimethyl 3 6-dihydro-3 ,6-methanophthalate (12) was effected slowly with concentrated aqueous ammonia at room temperature to give the diamide, m.p. 211-212'. This amide could not be obtained by the interaction of cyclopentadiene and acetylene dicarboxamide. 3 6-Dihydro-3,6-methunophthalonitrile.All attempts to prepare this nitrile by dehydration of the corresponding amide with acetic anhydride or phosphorus pentoxide failed. However, acetylenedicarbonitrile (carbon subnitride), prepared by a modification of the method of Moureu and Bongrand (ll),readily added to cyclopentadiene to give the desired nitrile, m.p. 4546". This dihydromet hanophthalonitrile is relatively unstable. It decomposes slowly even when stored in the absence of air and light. No confirmation of the structure of the adduct could be obtained by alkaline hydrolysis to a dibasic acid. Upon catalytic hydrogenation of the nitrile with a palladium catalyst two moles of hydrogen were absorbed to give a hexahydromethanophthalonitrile identical with that obtained in the hydrogenation of endo-cis-1,2 ,3 6-tetrahydro-3 6-methanophthalonitrile. An endo-cis-configuration for the hexahydrodinitrile is thus indicated as the result of a preferential exo-cis- addition of hydrogen to the A1double bond. Although the dihydrodinitrile might still be expected to possess dienophilic character, further tendency to add to a second molecule of cyclopentadiene was not observed. DERIVATIVES OF HEXAHYDRO-3,6-METHANOPHTHALIC ACID
endo-cis- and trans-Hexahydro-S16-methanophthalonitriles. Hydrogenation of both cis- and trans-l,2,3 6-tetrahydro-3 6-methanophthalonitriles, using colloidal palladium as a catalyst, took place smoothly. Both hexahydrodinitriles were obtained as white crystalline solids; the cis-isomer melting at 145.5-146", the trans-isomer a t 120-121".
3 4,5,6-TETRAHYDRO-3,6-METHANOPHTHALICACID Previous work by Diels and Alder (12) on the partial hydrogenation of 3,6dihydro-3 6-methanophthalic acid indicated that preferential addition of hydrogen to the A4 double bond may be readily carried out using colloidal palladium as a catalyst. A similar selective hydrogenation of 3,6-dihydro-3 6-methanophthalonitrile was performed. Only a slight change in the rate of absorption of hydrogen was observed after the addition of one mole. However, interruption of the hydrogenation after the addition of one mole of hydrogen always gave a DERIVATIVES OF
154
A. T. BLOMQUIST AND E. C. WINSLOW
white crystalline tetrahydrodinitrile melting at 34-36'. Alkaline hydrolysis of this nitrile failed to give a dibasic acid. Extensive decomposition with the liberation of hydrogen cyanide took place. This behavior is similar to that observed for the dihydromethanophthalonitrile. DERIVATIVES O F 3,6-BENZOHYDRILIDENEMETHANOPH!l'HALIC ACIDS
The addition of diphenylfulvene to fumaronitrile, maleonitrile, and acetylenedicarbonitrile was effected by heating the reactants in boiling benzene for onehalf hour. After removal of the benzene, the adducts separated after varying lengths of time from the resulting reddish, resinous mass as mustard colored crystals. This crystallization required several days with the adduct of fumaronitrile, twelve hours from the reaction mixture of maleonitrile, and occurred a t once in the reaction with acetylenedicarbonitrile. All of the fulvene adducts were readily purified by crystallization from alcohol. EXPERIMENTAL
trans-Dimethyl l,Z,S,6-tetrahydro-S,6-methanophthalate. Cyclopentadiene. Cyclopentadiene was prepared by a modification of the method of Perkins and Cruz (13) by distillation of dicyclopentadiene. Crude dicyclopentadiene' (m.p. 20") was carefully heated in a flask attached to anefficient fractionating columnso that the vapors of the distilling liquid did not rise above 45". No iron filings wereadded to the dicyclopentadiene to aid the pyrolysis. Since the pure monomer polymerizes readily on standing i t was always used in the freshly prepared state for all addition reactions. endo-cis-l,2, S,B-Tetrahydro-S,6-methanophthalic anhydride. This anhydride was obtained by the method of Diels and Alder (20) in practically quantitative yield, m.p. 164". trans-l,Z,S,6-Telrahydro-S,6-methanophthalyl chloride. Fumaryl chloride was prepared according to the method of Kyrides (14). T o a solution of 41 cc. (0.5 mole) of freshly distilled cyclopentadiene in50 cc. of anhydrous ether contained i n a 500-cc. round-bottomed flask equipped with stirrer, reflux condenser, thermometer, and dropping-funnel there was added a solution of 77 g. (0.5 mole) of fumaryl chloride in50 cc. of anhydrous ether. The addition was effected dropwise with stirring and efficient external cooling of the reaction mixture. The temperature of the reaction mixture was maintained a t 20" during the addition and allowed to come to room temperature at the end. After removal of excess ether and cyclopentadiene by distillation under reduced pressure, the residue was purified by fractional distillation under vacuum. There was obtained 91 g. (830/, yield) of the pure acid chloride boiling a t 114-118"/11 mm. trans-Dimethyl I ,,!?,S,6-tetrahydro-3,6-methanophthalate: ( A ) . From cis-l,Z, S,d-tetrahydro-3,6-methanophthalic anhydride (I). A solution of 32.8 g. (0.2 mole) of the cis-anhydride in 80 cc. (2.5 moles) of absolute methanol was refluxed gently for fifteen hours. During the first five hours of heating a slow stream of dry hydrogen chloride was passed through the solution. After removal of the hydrogen chloride and excess methanol, the residue was distilled in a vacuum. The yield of distilled ester, b.p. 119-120"/4 mm., was 33 g. (80%). Traces of the anhydride may be removed from the distilled ester by treatment with dry gaseous ammonia. The insoluble ammonium salt of the acid is precipitated and removed by filtration. The ester purified in this manner solidifies on standing, m.p. 37-39". (B). From trans-1 ,2,5,6-tetrahydro-S,6-methunophthulyl chloride. To 100 g. (0.5 mole) of the trans-acid chloride described above cooled to 5" was added 33 g. (1.03 moles) of absolute methanol, The addition was carried out dropwise and with stirring, maintaining the 1 The dicyclopentadiene used in these studies was furnished through the courtesy of the United States Steel Corporation.
UNSATURATED NITRILES IN THE DIENE SYNTHESIS
155
temperature below 30". The resulting mixture was washed with dilute sodium carbonate solution, water, and dried. Distillation of the crude dried product gave 90 g. (90%) of the pure ester, b.p. 119-120"/4 mm. trans-1,R,S,6-Tetrahydro-S,6-methanophthalamide. Dropwise addition with stirring of the trans-acid chloride to a large excess of concentrated aqueous ammonia gave directly the desired amide. The crude amide which separated from the reaction mixture was purified by recrystallization from water, m.p. 253-256" (decomp.). Anal. Calc'd for CoH12N202: N, 15.5. Found: N, 15.3. trans-l,R,S, 6-Tetrahydro-J,6-methanophthalonitrile. Fumaronitrzle. Fumaramide (m.p. 264-268")prepared either by ammonolysis of dimethyl fumarate or of fumaryl chloride was converted t o fumaronitrile by the method of de Wolf and van de Straete (IO). Rapid heating of a dry mixture of phosphorus pentoxide (30 9 . ) and fumaramide (11.4g.) at a pressure of 2 mm. gave a 7 g. (90%) yield of the desired fumaronitrile, m.p. 95-96'. Addition of fumaronitrile to cyclopentadiene. To a cooled solution (0') of 7.8 g. (0.1 mole) of fumaronitrile in 50 cc. of ethanol was added, with stirring, 9 cc. (0.11mole) of fresh11 distilled cyclopentadiene. The rate of addition was controlled so as not to exceed a reaction temperature of 35". After addition was complete the solution was concentrated t o one half its original volume by heating on a steam-bath. Upon cooling t o 0" and seeding with an ice crystal the adduct crystallized. The crude nitrile was recrystallized from ethanol and gave 13.2 g. (92%) of a pure product melting a t 95.5-96'. Ancl. Calc'd for CsH&z: N, 19.4. Found: N,19.35. endo-cis-1,d,S,6-Tetrahydro-S,6-methanophthalonitrile. Maleonitrile. Maleamide (m.p. 180-181")was obtained by the ammonolysis of methyl maleate with cold concentrated aqueous ammonia a t 10" in the dark (10). The crude maleamide, which is contaminated with some fumaramide, may be purified by treatment with cold methanol. The maleamide is less soluble than the fumaramide and may be easily isolated in the pure state. An intimate mixture of 25 g. of sea sand (previously washed and calcined), 11.4 g. (0.1 mole) of maleamide, and 50 g. of phosphorus pentoxide was placed in a 500-cc. roundbottomed flask attached by means of a short bent glass tube to a condenser and receiver (cooled in ice). The system was evacuated to a pressure of 2 mm. and the vacuum maintained throughout the course of the reaction. The contents of the flask were then heated directly and as strongly as possible with a Meker burner. Distillation began within a few minutes and heating was continued as long as the liquid continued to distill. The impure liquid maleonitrile (2 g., 39y0)was purified by crystallization from ethanol on cooling to -20". The purified material melted at 30-31". Addition of maleonitrile to cyclopentadiene. T o 4 cc. of freshly distilled cyclopentadiene contained in a test tube immersed i n a dry-ice cooling mixture there was added dropwise 1.5g. of maleonitrile. The addition was controlled so as to maintain the reaction temperature below 40". The crystalline precipitate, which separated after the addition had been completed, was separated by filtration and recrystallized from hot absolute ethanol. Dilution of the ethanol mother liquors from the recrystallization with ice gave an additional quantity of pure adduct. The yield was 2.6 g. (94%) of the pure nitrile, m.p. 155-156'. Anal. Calc'd for CSHsN2:N , 19.4. Found: N,19.3. ( A ) . By addition of maleimide to endo-cis-l,2,S,6-Tetrahydro-S,6-methanophthaEimide. cyclopentadiene. Maleimide was prepared according to the method of Rinkes (15) b y heating a mixture of maleamide and anhydrous zinc chloride at 200' under a pressure of 2 mm Maleimide was added to cyclopentadiene according to the procedure given for the addition of fumaronitrile to cyclopentadiene. The imide was obtained in 90% yields and melted at 184-185". Anal. Calc'd for CsHeNOr: K , 8 6. Found: N , 8.5. (B). From ammonium cis-l,~,~,6-tetrahydro-S,6-methanophthalate. cis-l,2,3,6-Tetrahydro-3,6-methanophthalicanhydride was converted t o the diammonium salt of the dibasic acid by treatment with concentrated aqueous ammonia. A mixture of 21.6 g. (0.1mole) of the dried ammonium salt was refluxed for two hours with 7 cc. of acetic anhydride.
156
A. T. BLOMQUIST AND E. C. TVINSLOTV
After cooling and neutralization of the reaction mixt,ure with 10% sodium hydroxide, the crude imide precipitated from the solution. The crude material was recrystallized from water after treatment u-ith iiorit, giving 12.9 g. (S$Yc)of the pure imide, m . p . iS4-185". h mixed melting point determinaCion with the product from (A) showed no depression. cis- and trans-Hexahydro-5,O-methanophthalonitdes. Both the cis- and trans- forms of 1,2,3,6-tetrahydro-3,6-methanophthalonitrile were subjected to catalytic hydrogenation in an ildams apparatus using colloidal palladium as a catalyst. Both reductions were carried out in ethanol solution. cis-l,2,3,6-Tetrahydro-3,6-methanophthalonitrile absorbed the theoretical quantit,y of hydrogen in fift,een minutes. Upon working up the reaction mixture in the usual way there was obtained after recrystallization from dilute ethanol the pure cis-hexahydronitrile, m.p. 145.5-146', in 80% yields. Anal. Calc'd for C91-Il~ii2: ii, 19.2. Found: Tu', 19.1. trans-l,2,3:6-Tetrahydro-3,6-methanophthalonitrilewas also reduced smoothly to the hexahydro derivative in fifteen minutes. The pure trans-hexahydrophthalonitrile was obtained as a white crystalline material, m.p. 120-121". Anal. Calc'd for C9€Il&,: S , 19.2. Found S, 6-Dihydro-3,6-methanophthalonitrile.Acetylenedicarboxamide (11). Dihromosuccinic acid was prepared by the method of Rhinesmith (16), and converted to the mono-potassium salt of acetylene dicarboxylic acid according to the method of Abbott (19). This potassium salt mas used to prepare dimethyl acetylenedicarboxylate as described by Hasbrouck (17). Starting with 125 g. of fumaric acid,51 g. of dimethyl acetylenedicarboxylate was obtained, which corresponds to an over-all yield of 33%. T o 80 cc. of concentrated aqueous ammonia cooled t o -10" was added with vigorous stirring 20 g. (0.14 mole) of dimethyl acetylenedicarboxylate. After agitating for,one hour, the precipitated amide was filtered, washed with a few cc. of ethanol, and dried for two days i n a vacuum desiccator. Thirteen grams (83%) of the dry product, m.p. 290-292", was obtained . Acetylenedicarbonitrile (If). An intimate mixture of 6 g. of pure dry acetylenedicarboxamide, 100 g. of fine sea sand (dried and calcined), and 50 g. of phosphorus pentoxide was prepared. The mixture was divided into four equal parts and placed in four test tubes 21 mm. i n diameter and 22 em. i n length. These test tubes were attached by rubber stoppers t o a specially constructed piece of apparatus consisting of a horizontal length of 16 mm. Pyrex tubing from which depended four parallel, adjacent side-tubes. One end of the horizontal tube was closed with a stopcock and the other end tapered to a diameter of 8 mm. At a distance of 5 inches from the taper, the 8 mm. tube was bent downward a t a90" angle. To the vertical 8 mm. tube was attached a fifth test tube fitted with a stopcock sidearm. This test tube served as a receiver during the distillation process. The entire system was evacuated to 2 mm. pressure, filled with carbon dioxide, and again evacuated, a pressure of 2 mm. being maintained i n the apparatus throughout the subsequent operations. The receiving test tube was then cooled to -80". -4heating-bath (215') was then applied suddenly to the four charged test tubes. Distillation of acetylenedicarbonitrile took place at once and was essentially complete in fifteen minutes. The product appeared as white crystals in the receiver. The yield was 1.5 g., 37%. Addition of acetylenedicarbonitrile to cyctopentadiene. To 4 cc. of freshly distilled cyclopentadiene was added dropwise 1.5 g. of acetylenedicarbonitrile as prepared in the preceding section. The temperature of the reaction mixture was kept below 20" during the addition. After complete addition, the mixture was poured onto a watch glass and excess cyclopentadiene allowed to evaporate. The residual crystals of crude adduct were recrystallized from the minimum quantity of aqueous ethanol. A second recrystallization from dilute ethanol gave 2.3 g. yield) of the pure 3,6-dihydro-3,6-methanophthalonitrile, m.p. 44-45". L4~aZ. Calc'd for CgHgN2: K, 19.7. Found: K , 19.0.
WNSATURATED NITRILES IN THE DIENE SYNTHESIS
157
d,6-Dihydro-J,6-methanophthala"de. T o 25 g. (0.17mo1e)'of dimethyl acetylenedicarboxylate was added dropwise 16.4 cc. (0.2mole) of freshly distilled cyclopentadiene. T o the resulting impure adduct was added 200 cc. of concentrated aqueous ammonia. The mixture was stirred for eight hours, the precipitated diamide filtered, and washed with cold water. Two recrystallizations from absolute ethanol resulted in 25 g. (83y0)of the pure diamide, m.p. 211-212'. Anal. Calc'd for CsHlohT202: N, 15.7. Found: 5 , 15.7. t rans-1,2,d,6-Tetrahydro-S,6-benzohydrilidenemethanophthalonitrile. T o a solution of 2.5 g. (0.01mole) of diphenylfulvene (18)in 25 cc. of benzene was added 0.8 g. (0.01mole) of fumaronitrile. The mixture was refluxed for an hour in the steam-bath and the benzene removed by distillation. From the resulting red resinous mass, yellow crystals separated after a week. This impure material was recrystallized three times from ethanol and once from petroleum ether. The yield was 0.8 g. (25%) of the pure adduct, m.p. 142-142.5' (decomp.). Anal. Calc'd for C22H1&2: N , 9.1. Found: N,9.05. exo-cis-i , 2 >3,6-Tetrahydro-d, 6-benzohydrilidenemethanophthalonitl.ile.The preparation of this adduct was carried out in exactly the same manner as that described in the preceding section for the trans adduct. Maleonitrile was substituted for fumaronitrile. Only one recrystallization was required to obtain a pure product. The pure adduct was obtained in 469; yield and melted a t 172-173" (decomp.). Anal. Calc'd for C22H16h-2: S , 9.1. Found: K,9.0. S,6-Dzhydro-~,6-benzohydrilidenemethanophthalonitrile. This preparation was carried out as described in the preceding sections using acetylenedicarbonitrile. I n this case no transient highly colored mass was observed. The adduct is readily purified by crystallization from ethanol. A 6170 yield of the pure adduct as yellow crysthls was obtained, m.p. 168-169". Anal. Calc'd for C22H14IC2: N, 9.2. Found: N,9.0. Resolution of trans-1,.2,S, B-tetrahydro-S,6-methanophthalicacid. T o a warm solution of 39.6 g. (0.1 mole) of anhydrous brucine in 200 cc. of distilled water was added 9.1 g. (0.05 mole) of trans-l,2,3,6-tetrahydro-3,6-methanophthalic acid, m.p. 186-187°. The warm solution was filtered and the clear filtrate allowed to stand four hours. The crystalline salt was filtered, and showed [a]:-48". Using water equal to twice the weight of the dried salt, careful recrystallization "as carried out until a constant value for the specific rottrtion was obtained. A constant value of [a]: -35" was observed. This maximum rot:ttion for the salt was obtained after the fifteenth primary recrystallization. Twelve additional primary recrystallizations were carried out t o ensure purity. Three grams of the resolved brucine salt, obtained after twenty-seven primary crystallizations, was dissolved in 25 cc. of water and converted into the free acid by treatment with 5 iV sodium hydroxide, to precipitate the brucine, followed by subsequent acidification of the aqueous filtrate with concentrated hydrochloric acid. The precipitated acid was filtered and recrystallized from 5 cc. of water. One-tenth gram of pure active acid, m.p. 166-168" was obtained. The optical rotation of the free acid was determined in acetone solution. Using a special polarimeter tube one decimeter in length with a volume of about 0.7 ec., a n observed rotation of aD 3.99"was noted. This gave [a]: +89.0" for the pure trans-1,2,3,6-tetrahydro-3,6-methanophthalic acid.
+
SUMMARY
1 . The behavior of fumaronitrile, maleonitrile, and acetylenedicarbonitrile as dienophiles in the Diels-Alder reaction with cyclopentadiene and diphenylfulvene has been studied. 2. Certain chemical and stereochemical studies of these dinitrile adducts and other related compounds have been made. The trans-configuration for the 1,2,
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A. T. BLOMQUIST AND E. C. WINSLOW
3,6-tetrahydro-3,6-methanophthalic acid, map. 186-187", has been confirmed by resolution of its brucine salt. 3. Preliminary insecticidal tests on the various nitriles derived from 3,6dihydro-3,6-methanophthalonitriileindicate that some of them are effective as contact poisons for certain species of insects. Those nitriles which contain a A4 double bond appear to be the most active. ITHACA, N. Y. REFERENCES (1) MCCRONE, Thesis, Cornel1 University, September (1942). (2) PHILIPS, SWINGLE, et al., U . S . Dep. Agr. Bur. Entomol. Plant Quarantine: Mimeo. Pub. E-548, (1941). (3) ALDERAND STEIN, Angew. Chem., 60,510 (1937). (4) NORTON,Chem. Rev., 91,319 (1942). (5) ALDER,STEIN,LIEBMANN, AND ROLLAND, Ann., 814,197 (1934). (6) OTT, Urg. Syntheses, Coll. Vol. 11, 528 (1943). AND MILLER,U. S. Patent 1974845;Chem. Abstr., M, 7265 (1934). (7) CLEMMENSON (8)ALDER,STEIN,ECKARDT, BUDDENBROCK, AND SCHNEIDER, Ann., 604, 216 (1933). (9) MORGAN, TIPSON, LOWY,AND BALDWIN, J. Am. Chem. SOC.,66,404 (1944). (10)DE WOLF AND VAN DE STRAETE, Bull. sci. acad. roy. Belg., 21,216 (1935). (11) MOUREU AND BONGRAND, Ann. chim., l4,5 (1920). (12) DIELS,ALDER,AND NIENBURG, Ann..,490,236 (1931). (13) PERKINS A N D CRUZ, J. Am. Chem. SOC.,49,518 (1927). (14) KYRIDES,Org. Syntheses, Coll. Vol. 11,177 (1943). (15) RINKES,Rec. trav. chim., 48, 960 (1929). (16) RHINESMITH, Urg. Syntheses, Coll. Vol. 11, 177 (1943). (17) HASBROUCK, Thesis, Cornell University, May (1942). (18) THIELE,Ber., 93, 666 (1900). (19) ABBOTT,Urg. Syntheses, Coll. Vol. 11, 10 (1943). (20) DIELSAND ALDER,Ann., W , 9 8 (1928).
